1. Field of Technology
The present application relates to a family of resettable circuit breakers that include a reset lockout operation and optionally an independent trip operation, and to power distribution systems in which such circuit breakers are utilized. More particularly, the present application is directed to circuit breakers that include a reset lock out capable of preventing the circuit breaker from resetting if a circuit interrupting portion used for fault protection is not functioning properly and/or if an open neutral condition exists. In addition, a trip portion may be added to the circuit breaker to permit the breaker to be tripped independent of the operation of the circuit interrupting portion.
2. Description of the Related Art
The electrical wiring device industry has witnessed an increasing call for circuit interrupting devices or systems which are designed to interrupt power to various loads, such as household appliances, consumer electrical products and branch circuits. In particular, electrical codes require electrical circuits in home bathrooms and kitchens to be equipped with ground fault circuit protection. Presently available GFCI devices, such as the GFCI receptacle described in commonly owned U.S. Pat. No. 4,595,894, use an electrically activated trip mechanism to mechanically break an electrical connection between one or more input and output conductors. Such devices are resettable after they are tripped by, for example, the detection of a ground fault. In the device discussed in the '894 patent, the trip mechanism used to cause the mechanical breaking of the circuit (i.e., the connection between input and output conductors) includes a solenoid (or trip coil). A test button is used to test the trip mechanism and circuitry used to sense faults, and a reset button is used to reset the electrical connection between input and output conductors.
However, instances may arise where an abnormal condition, caused by for example a lightning strike, occurs which may result not only in a surge of electricity at the device and a tripping of the device but also a disabling of the trip mechanism used to cause the breaking of the circuit. This may occur without the knowledge of the user. Under such circumstances, an unknowing user faced with a GFCI which has tripped may press the reset button which, in turn, will cause the device with an inoperative trip mechanism to reset without the ground fault protection available.
Further, an open neutral condition, which is defined in Underwriters Laboratories (UL) Standard PAG 943A, may exist with the electrical wires supplying electrical power to such GFCI devices. If an open neutral condition exists with the neutral wire on the line (versus load) side of the GFCI device, an instance may arise where a current path is created from the phase (or hot) wire supplying power to the GFCI device through the load side of the device and a person to ground. In the event that an open neutral condition exists, current GFCI devices which have tripped, may be reset even though the open neutral condition may remain.
Commonly owned application Ser. No. 09/138,955, filed Aug. 24, 1998, which is incorporated herein in its entirety by reference, describes a family of resettable circuit interrupting devices capable of locking out the reset portion of the device if the circuit interrupting portion is non-operational or if an open neutral condition exists. Commonly owned application Ser. No. 09/175,228, filed Oct. 20, 1998, which is incorporated herein in its entirety by reference, describes a family of resettable circuit interrupting devices capable of locking out the reset portion of the device if the circuit interrupting portion is non-operational or if an open neutral condition exists and capable of breaking electrical conductive paths independent of the operation of the circuit interrupting portion.
Current resettable circuit breakers with fault protection capabilities, such as the HOM-GFI series of GFCI circuit breakers manufactured by Square-D Company, Palatine, Ill., have line and load power and neutral connections and a switch for controlling power distribution to a load. To provide fault protection, such circuit breakers have sense circuitry and linkage to the switch, which are capable of sensing faults (e.g., ground faults) between the load power and the line neutral conductors and opening the switch. A test button accessible from an exterior of the breaker is used to test the operation of the fault protection portion of the breaker when depressed. However, like conventional resettable receptacles, conventional resettable circuit breakers do not include either a reset lockout or an independent trip portion.